Subtraction alert: the HP-42S was introduced in 1988, not 1998 (the 25th anniversary part is correct). :-)
The HP-42S has been my daily driver since the spring of 1989. When it dies, I will have to retire. (Actually, that's why I have Free42 on all three computers and my iPhone.)
I continued to use my HP-41CX in parallel through the mid 1990s, primarily because of the modules and other unique capabilities. I sometimes now use my HP-48G+ and HP-35S for certain things, but most of my other HP's don't get used very often.
I agree that the HP-42S is the best RPN scientific calculator ever, but it could have been better. First, ALL of the native HP-41CX capabilities plus the Advantage ROM should have been included in the HP-42S, and that includes full I/O and putting the alphabet on the keys not hot keys. In addition, if I could pick one thing from the 48 series to add, it would be units. While I understand all the enthusiasm for reintroducing the HP-15C, the real need IMHO is a reintroduced and enhanced HP-42S, including a better display and more memory.